Modeling the Impact of Climate Change on the Distribution of the Cilician Water Frog Lineage (Pelophylax cf. bedriagae 1) in the Çukurova Plain in Southeastern Türkiye and Implications for Its Future Projections

Abstract

Climate change presents a considerable challenge to biodiversity, with amphibians being particularly susceptible due to their sensitivity to environmental changes. One of these amphibian groups is the Anatolian water frog complex (genus: Pelophylax), a distinct, genetically and phylogenetically differentiated cryptic species whose members are morphologically indistinguishable. In this group, the Cilician water frog lineage (Pelophylax cf. bedriagae 1) is of particular interest as it is only found in the biodiversity-rich Çukurova Plain in southeastern Türkiye; it faces dual threats from historical overharvesting and impending climate change. In this study, we utilized Maximum Entropy (MaxEnt) modeling to map the Cilician lineage’s current habitat suitability and distribution, identify key environmental drivers, and project future range shifts under various climate change scenarios. We compiled 167 georeferenced occurrence records and initially assembled 17 environmental predictors (climatic, topographic, and hydrological). Through a rigorous optimization process, including variable selection (varSel and reduceVar functions) and hyperparameter tuning, the model was refined to utilize the seven most influential predictors, substantially improving its predictive accuracy. Permutation and jackknife tests identified temperature seasonality, minimum temperature of the cold quarter, annual precipitation, ruggedness, slope, and distance to lake as the most important variables influencing the frog’s distribution. Response curves further elucidated the specific ecological niche characteristics shaped by these factors. Projections for 2050, 2080, and 2100 under low (GCM-245) and high (GCM-585) carbon emission scenarios consistently predict a pronounced northward shift in the suitable habitat of the Cilician water frog lineage. This shift is accompanied by increased habitat fragmentation and a notable decline in suitability within the lineage’s current core range, particularly under the high-emission pathway. Whereas the total climatically suitable area may increase in newly favourable northern regions, the lineage’s ability to colonize these areas depends on landscape connectivity and dispersal capabilities. This raises concerns about its potential invasiveness in new ecosystems. Our findings emphasize the need for targeted, adaptive conservation strategies that mitigate the impact of climate change and account for human-induced habitat alterations to ensure the long-term persistence of this narrowly distributed water frog lineage.